[c-nsp] Dual-homing without BGP

Tim Franklin tim at colt.net
Thu Feb 16 11:55:49 EST 2006

> well, but Vincent just does not want what multihoming gives 
> him, he does
> not want to use the redundancy via the 2Mbit link, so I think PBR
> (which, BTW, has been cef/interrupt switched for a looong 
> time now) will
> do just what he wants. or am I missing something?

Missing that, irrespective of which switching path it's now in, the
reputation of PBR as slow, flakey and scary often remains? ;)

I'm not a particular fan of PBR, and a lot of the cases where I see it
proposed are trying to solve the wrong problem, but it *does* have its uses,
and this might be one of them.

Given two links to the same provider (or some *really* nice inter-provider
cooperation), I'd be inclined to split the /23 in half, put the important
servers on one half and the streamers on the other.  Announce the ecommerce
/24 only out of the good link, announce the ecommerce /24
prepended/MED'd/whatevered and the streaming /24 out of the cheap link.
(The single provider or cooperating providers means there's still only a /23
annoucement (or two) makes it out into the "Internet" routing table).

For outgoing, run two HSRP groups across the T and N routers.  Ecommerce has
the virtual address with T primary as its default gateway, streaming has the
N virtual address.

For two unconnected providers though, the multiple annoucements probably
ammount to pissing in the routing pool :(


____________   Tim Franklin                 e: tim at colt.net 
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